The present invention relates to a throttle body and control system for a vehicle. More specifically the present invention relates to a control method and apparatus for controlling the position of a throttle plate in a throttle body.
Electronic engine control has evolved from a relatively elementary control system employing simple switches and analog devices to a highly precise fuel and ignition control system employing powerful microprocessors or microcontrollers. The miniaturization and cost reduction of powerful electronics has put the power of the computer age into the hands of automotive engineers. Microprocessors have allowed complex programs involving numerous variables to be used in the control of present day combustion engines, leading to better engine control and performance.
An important facet of combustion engine control is the regulation of air flow into a cylinder by a throttle and accordingly the quantity of fuel delivered into the cylinder. In a combustion engine a throttle, having a movable throttle plate, directly regulates the power produced by the combustion engine at any operating condition by regulating the air flow into the engine. The throttle plate is positioned to increase or decrease air flow into the engine. The engine acts as an air pump with the mass flow rate of air entering the engine varying directly with throttle plate angular position. Presently, there is a need in the art to precisely control throttle plate position in a throttle body to tightly regulate the flow of air and fuel into a cylinder.
In the operation of a standard vehicle combustion engine, a driver will depress the accelerator pedal to generate a portion of a throttle plate position command that varies the throttle plate angle and accordingly varies the air flow into the engine. Other factors besides driver pedal input such as engine temperature, engine speed, exhaust gas oxygen, exhaust gas recirculation valve position, air flow into the engine, and other similar variables will also factor into the a throttle plate position command, but are not limited to such. A control unit coupled to a fuel injector, monitoring the variables cited above, will regulate the fuel that is mixed with the air, such that the injected fuel generally increases in proportion to air flow. If a carburetor is used the air flow through the carburetor will directly regulate the amount of fuel mixed with the air, with respect to the vacuum or suction formed by the air flow through the throttle body. For any given fuel-air mixture, the power produced by the combustion engine is directly proportional to the mass flow rate of air into the engine controlled by the throttle plate position.